1. Field of the Invention
The present invention relates to a supporting structure for an instrument panel of a motor vehicle, and more particularly, to a structure for supporting an instrument panel by a defroster nozzle.
2. Description of the Related Art
An automotive air conditioner provides a comfortable environment for occupants of the vehicle in all climatic and driving conditions, prevents fogging and frosting of the windshield etc. to secure the driver's range of vision, and also permits safe and comfortable driving, and thus most of motor vehicles are equipped with an air conditioner. The air conditioner is usually arranged in the vehicle body at a location under an approximately central portion of the instrument panel, and conditioned air is guided through an air duct arranged inside the instrument panel and let out from vents located in the vehicle compartment. Also, a defroster is provided for eliminating fogging of the windshield and adapted to eject warm air toward the inside of the windshield from thereunder, thus removing fogging of the inside of the windshield.
The air conditioned by the air conditioner flows up toward the vents while pushing the ceiling wall of the air duct upward, and thus the joint between the inlet of the air duct and the air outlet may possibly become separated, causing leakage of the air. To prevent this, an air conditioner air duct has been proposed wherein the air duct arranged inside the instrument panel is provided with a rib, as an abutment, which is disposed in contact with the inside surface of the top of the instrument panel (see Unexamined Japanese Patent Publication No. H08-118942 (hereinafter referred to as Patent Document 1), for example).
The instrument panel is arranged along the overall width of the driver's and front passenger's seats of the vehicle, and a front end portion thereof extends to the bottom of the windshield and is provided with an opening for a defroster nozzle. Usually, the instrument panel is a resin molded article and has a reinforced structure such that the instrument panel is supported at its front portion by a deck cross member through brackets, supported at its rear portion by brackets extended downward from the deck cross member, and supported at its both sides by front pillars. However, the offset of the central portion of the instrument panel from the deck cross member is large, giving rise to a problem that the central portion is liable to be bent or warped because of its low rigidity. Especially in the case of a wide deck type instrument panel having an increased dimension between its front and rear ends, the rigidity of the central portion is noticeably low.
A rib may be formed on the inside surface (underside) of the instrument panel near the central portion thereof so that the central portion may be supported by the air duct etc. of the air conditioner located under the instrument panel. If such a rib is formed on the inside surface of the instrument panel, however, a problem arises in that a sink mark may appear on the outside surface of the instrument panel, impairing the appearance. Also, in the case where there is a considerable distance (large space) between the instrument panel and the air duct etc., the rib needs to be lengthened, which leads to poor moldability. Further, in the case of the structure disclosed in Patent Document 1 wherein the air conditioner air duct is provided with a rib which is disposed in contact with the inside surface of the top of the instrument panel, not only the moldability is poor but a wide area cannot be secured for supporting the instrument panel. With this structure, it is difficult to increase the rigidity of the top of, in particular, a wide deck type instrument panel.